Netflix doesn’t want anyone to know how many people watch its original shows, like “House of Cards” and “Orange Is the New Black.”

But until a few months ago, at least one company had a pretty good idea — and shared it publicly. Now Netflix has plugged that leak.

Procera Networks, a broadband monitoring company, says it was able to track individual shows Netflix users streamed on multiple Internet networks for several days at a time. It published its findings on a company blog three times: When Netflix launched “House of Cards” and “Arrested Development” in 2013, and this year, when the company streamed its second season of “House of Cards.”

Procera couldn’t provide overall viewership numbers for Netflix’s shows, but could at least provide directional information, by showing how they performed on several of its client’s networks. This year, for instance, it concluded that “five percent to 15 percent of Netflix subscribers on several worldwide broadband networks” watched at least one episode of the second season of “House of Cards” when that show launched.

Netflix never commented on Procera’s posts, just like it never comments on other attempts to figure out how many people are watching its shows, which usually involve polling Netflix users about their viewing habits. But the company appears to have tacitly acknowledged that Procera’s data was accurate, because it has taken steps to cut Procera off.

Procera works for Internet providers like cable and wireless companies, which want to know how their pipes are performing, and in some cases what’s being sent through the pipes, using “deep packet inspection.” It used to be able to pick out individual Netflix files, because Netflix had labeled them in a way that identified the show and the resolution they were streaming in, says Cam Cullen, who heads up marketing for Procera.

Cullen says Netflix didn’t complain about Procera’s snooping. “They never told us explicitly not to do that,” he said.

And he guesses that Netflix wasn’t entirely unhappy that Procera published the data it rounded up — particularly when it reported that “Arrested Development,” though panned by critics, had generated big viewership. Procera said 36 percent of devices on one client’s network had streamed an episode of the show the first weekend it debuted.

But Cullen says that Netflix employees eventually told Procera that they would shut its analytical window. “They said, ‘we’re eventually going to change that and make it hard for you to do that,'” he said.

That happened in late spring, when Netflix began anonymizing its files. You can see evidence of Netflix’s plans via release notes the company sent to broadband providers that work with the company’s Open Connect data network; Netflix told partners that new software would “further protect content and utilization information,” and “may minimize the accuracy of devices that perform DPI or traffic reporting.”

Cullen says the update was in place before Netflix launched the second season of “Orange Is the New Black” in June, which is why his company hasn’t been able to tell how well that show has performed. “At the end of the day, I think they want to be the only ones that have that information.”

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